Systemic Sclerosis
Systemic sclerosis (also known as SSc or scleroderma) is a severe rheumatologic illness with inflammation of small and medium sized vessels throughout the body that causes cycles of ischemic injury, neovascularization, and progressive scarring in the skin and visceral organs. Current diagnostic criteria are dependent on physical findings combined with autoantibodies (ANA combined with Scl-70 and anti-centromere B) that are not believed to be directly involved in the pathogenesis of the disease. In addition to suboptimal diagnostic tests for systemic sclerosis, there is no effective therapy currently available for this disease.
Investigations into systemic sclerosis have not identified the cause of a presumed autoimmune attack on small and medium sized vessels, but have identified the effector cell type responsible for the immune-mediated damage. In 2009, investigators showed that systemic sclerosis patients have a unique CD8 T cell population in peripheral blood and skin that produce the protein interleukin 13 (IL-13) when activated (hereafter referred to as CD8IL-13 T cells). In addition, studies have shown that dermal fibroblasts exposed to culture supernatants from scleroderma CD8 T cells produce collagen (which results in scarring) through a mechanism dependent on IL-13 and tumor necrosis factor beta (TGF-beta), which is the master cytokine involved in collagen production and scarring. Others investigating mechanisms of scarring in other experimental systems have shown that the combination of tumor necrosis factor alpha (TNF-alpha) and IL-13 causes stromal cells to make TGF-beta. Unfortunately, however, the IL-13 producing CD8 T cells in human studies could only be identified by activation, fixation/permeabilization/intracellular cytokine staining for IL-13. That processing requirement has conventionally rendered the accessible CD8IL-13 T cell population unusable for advanced investigations such as gene expression micro array analyses.
Chlamydia Infection
Chlamydia infection is the most common sexually transmitted disease, responsible for about 2.8 million cases a year in the US. Untreated Chlamydia infections can ascend into the upper reproductive tract causing scarring and fibrosis that result in infertility and ectopic pregnancies. Fibrosis is a major contributor to scarring (the shared biologic trait shared with scleroderma) caused by Chlamydia infection.
Working in the mouse model for Chlamydia trachomatis infections, the inventor of the present application developed unique methodologies for cloning antigen-specific T cell clones based on unconventional antigen preparations and antigen presenting cells. Chlamydia infections of the genital tract are clinically important because the infection-promoted scarring of the genital tract that leads to infertility and ectopic pregnancy.
It is conventionally known that T cells, and specifically CD8 T cells, are the predominant inflammatory infiltrate in affected tissue thought to produce cytokines that drive the synthesis of extracellular matrix proteins by fibroblasts that results in excess fibrosis. Research in the mouse model for Chlamydia genital tract infections has shown unambiguously that scarring and infertility are mediated by CD8 T cells. Perhaps more specifically, the inventor hereof has shown in the mouse model that the CD8 T cell response to Chlamydia genital tract infections is atypical and includes the antigen-specific CD8IL-13 T cells that also produce TNF-alpha when activated.
As previously noted, although human CD8+ T cells expressing IL-13 have been described in humans, they unfortunately are not currently a usable tool to study the biology, protein, and gene expression in these cells, nor to screen prospective therapeutics. This is in large part because convention human CD8IL-13 T cell subset biomarkers do not allow for the practicable purification of viable CD8IL-13 T cells required to perform the genomic and functional studies needed to develop improved diagnostic tests, test therapeutic drugs, and identify new therapeutic targets.
Accordingly, and especially given the huge impact that both Chlamydia infections and scleroderma have on human health and the problems that exist with currently available treatments for both conditions, there is a pressing need for an increased understanding of the role of CD8 T cells in the human immune system and, more specifically, for a useful tool to study CD8IL-13 T cells. Similarly, a need exists to identify biomarkers for human CD8IL-13 T cells, with such biomarkers capable of facilitating viable cell purification protocols such that genomic and functional studies may be performed thereon. In this manner, meaningful diagnostic testing and therapeutic interventions could be screened for the purposes of (a) vaccine development, (b) diagnosing and treating pathological scarring during Chlamydia infections, and (c) diagnosing and treating pathological scarring in patients with scleroderma. As provided herein, gene expression microarray experiments utilizing murine CD8IL-13 and conventional CD8 T cell clones have been used to identify biomarkers for human CD8IL-13 T cells. The inventor of this application has identified that the human homolog (C10orf128) of the murine cell surface biomarker for CD8IL-13 T cells (1810011H11Rik) is expressed in the circulating CD8 T cell pool of patients with scleroderma, and can be practicably used to purify the desired CD8IL-13 T cell subset from the peripheral blood of human subjects.